1. Field of the Invention
The present invention relates to an electrostatic-latent-image developing toner that is used for developing electrostatic latent images in processes such as an electronic photographing process, an electrostatic recording process and an electrostatic printing process.
2. Description of the Related Art
Conventionally, the electrostatic-latent-image developing toner, which contains at least a binding resin, a coloring agent and a wax, is prepared by using a method such as a so-called pulverizing method, a suspension polymerization method, an emulsion polymerizing coagulation method and an emulsion dispersing method. With respect to the wax, commercially available wax, such polyethylene wax, oxidation-type polyethylene wax, polypropylene wax, oxidation-type polypropylene wax and carnauba wax, is generally used. In general, an image-forming device which uses such a toner is provided with a cleaning mechanism for cleaning residual toner on the surface of a photosensitive member.
However, even when the conventional toner is used in an image-forming apparatus provided with such a cleaning mechanism, fused toner and residual toner after cleaning process are generated, failing to carry out a sufficient cleaning process. Such an insufficient cleaning process causes a defective image portion on an image due to the defective cleaning operation.
In particular, the toner granulated by using the emulsion polymerizing coagulation method tends to be susceptible to insufficient cleaning, and has a narrower permissible range of waxes to be used, with the result that a complicated wax selection is required.
The conventional toner tends to easily adhere to members such as a developing roller, a fixing roller and a developing sleeve, causing problems of insufficient charging, insufficient fixing and image losses.
Furthermore, the conventional toner tends to cause a problem of roughness due to granular density irregularities that appear on an image obtained after the fixing process (hereinafter, referred to as “granular noise”).
Therefore, in order to obtain a good image, a toner which contains a specific ester compound as a wax has been proposed (for example, Japanese Patent Laid-Open Publication No. 2001-318484 (pages 2 to 3)). The application of the toner of this type caused the granular noise during endurance printing processes, although it can prevent the granular noise in the initial stage. Moreover, although the cleaning property is slightly improved, it is still insufficient. The problem of insufficient cleaning is particularly conspicuous at the time of the endurance printing processes.